2,3,3,3-Tetrafluoropropene, which is one of the halopropenes and represented by the chemical formula CF3CF═CH2 (HFC-1234yf), is a compound useful as a refrigerant, and is drawing attention as a constituent of a refrigerant or mixed refrigerant that can be used as an alternative for chlorofluorocarbon.
As one example of a method for producing HFC-1234yf, Patent Literature 1 discloses a method comprising reacting CF3CH═CHF (HFC-1234ze-E) in the presence of a Cr catalyst in a gas phase, thereby directly producing CF3CF═CH2 (HFC-1234yf). However, this method is in need of improvement because of low yield. Non-Patent Literature 1 discloses a method comprising reacting a compound represented by the chemical formula CF3CF2CH2X (X=Cl or I) with zinc (Zn) in ethanol, thereby producing HFC-1234yf in a single reaction step. However, this method is not suitable for industrial production because of the high cost of zinc, and the production of large amounts of waste.
Other examples of methods for producing HFC-1234yf include the following. Patent Literature 2 discloses a method comprising reacting chloromethyl tetrafluoropropanate with amine; Patent Literature 3 discloses a method comprising the thermal decomposition of 1-trifluoromethyl-1,2,2-trifluorocyclobutane; Patent Literature 4 discloses a method comprising reacting chlorotrifluoroethylene (CClF═CF2) and methyl fluoride (CH3F) in the presence of a Lewis acid such as SbF5; and Patent Literature 5 discloses a method comprising the thermal decomposition of tetrafluoroethylene (CF2═CF2) and chloromethane (CH3Cl). Non-Patent Literatures 2 and 3 listed below also disclose HFC-1234yf production methods.
However, such methods are not considered to be effective for industrial production since the starting materials are difficult to produce and are not easily obtained, the reaction conditions are severe, the reaction reagents are expensive, the yield is low, etc.
Further, Patent Literature 6 discloses a method comprising reacting 2-chloro-3,3,3-trifluoropropene represented by the chemical formula: CF3CCl═CH2 (HCFC-1233xf) with hydrogen fluoride in a gas phase under a pressurized condition, thereby producing HFC-1234yf. However, the selectivity of the target compound HFC-1234yf is about 40 to about 60%; therefore, this method is not considered a production method of HFC-1234yf with high selectivity.
Citation List
Patent Literature                PTL 1: US 2008/0058562 A1        PTL 2: Japanese Unexamined Patent Publication No. S63-211245        PTL 3: U.S. Pat. No. 3,996,299        PTL 4: US 2006/258891 A1        PTL 5: U.S. Pat. No. 2,931,840        PTL 6: WO2009/003084 A1        
Non Patent Literatures                NPL 1: J. Chem. Soc., 1957, 2193-2197        NPL 2: J. Chem. Soc., 1970, 3, 414-421        NPL 3: J. Fluorine Chem., 1997, 82, 171-174        